aianjie

 

11、The return on a portfolio is normally distributed with a mean return of 8 percent and a standard deviation of 18 percent. Which of the following is closest to the probability that the return on the portfolio will be between -27.3 percent and 37.7 percent?

A) 92.5%.

B) 68.0%.

C) 81.5%.

D) 96.5%.

aianjie

 

10、Given the probabilities N(–0.5) = 0.3085, N(0.75) = 0.7734, and N(1.50) = 0.9332 from a z-table, the probability of 0.2266 corresponds to:

A) N(–0.25). 

B) N(–0.75). 

C) N(0.25). 

D) N(0.50).

aianjie

 

The correct answer is B

This problem is checking your knowledge of a normal distribution and gives you more information than you need to answer the question. The area of a normal distribution is 1, with two symmetric halves that equal 0.5 each. N(0.75) means that the area to the left of 0.75 on the positive portion of the curve is 0.7734. This means that the area to the right of 0.75 is (1.0 – 0.7734) = 0.2266. Since the halves of a normal distribution are symmetrical, that means the area to the left of (–0.75) is also 0.2266.

aianjie

 

9、For a normal distribution, what approximate percentage of the observations falls within ± 2 standard deviations of the mean?

A) 95%.

B) 99%.

C) 92%. 

D) 90%.

aianjie

 

The correct answer is A

For normal distributions, approximately 95 percent of the observations fall within ± 2 standard deviations of the mean.

aianjie

 

The correct answer is B

 

 

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2009-6-25 11:13

aianjie

 

8、Approximately 50 percent of all observations for a normally distributed random variable fall in the interval: fficeffice" />

 

 

A) 

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2009-6-25 11:10

 

B) 

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2009-6-25 11:10

 

C)  gif,3.gif]UploadFile/2009-6/20096251110733107.gif[/upload]

 

D)  [upload=

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[2008] Topic 5: Some Important Probability Distributions 相关习题

2009-6-25 11:10

 

aianjie

 

The correct answer is B

z = (180,000 – 280,000)/40,000 = –2.50. Using the z-table, F(–2.50) = (1 – 0.9938) = 0.62%.

aianjie

 

The correct answer is D

z = (350,000 – 280,000)/40,000 = 1.75. Using the z-table, F(1.75) = 0.9599. So, the percentage greater than $350,000 = (1 – 0.9599) = 4.0%.

aianjie

 

The percentage of hedge fund investors with income less than $180,000 is closest to:

A) 1.15%.

B) 0.62%.

C) 2.50%.

D) 6.48%.